Human body malodors are generally believed to be caused in part by microbial interaction with sweat gland secretions which produces pungent fatty acids. Aside from cleansing, one way such odors are controlled is by the use of deodorant products, particularly in the underarm area of the body.
Deodorant products generally consist of a safe and effective level of an antimicrobial active ingredient which is incorporated into a vehicle from which the active ingredient may be deposited on the skin. A deodorant product may be in on of several forms including, for example, liquids, solid wax sticks or gel sticks. The present invention relates to gel stick deodorant compositions.
Gel stick deodorant compositions have several advantages over other types of stick formulations. For example, they usually leave no more than a minimal amount of residue on the skin, and they glide easily over the skin when applied. Deodorant compositions of the gel stick type generally incorporate three key ingredients: a material known to have deodorant efficacy, a gelling agent, and a polar solvent system.
The gelling agents used most often in deodorant gel stick compositions ar of the fatty acid soap type. The gelling agents used in these compositions include, for instance, the sodium or potassium salts of C.sub.12 -C.sub.18 fatty acids. Soap/alcohol gels which provide the benefits, discussed above, examples of which are disclosed in U.S. Pat. No. 2,732,327, Teller, issued Jan. 24, 1956; U.S. Pat. No. 2,857,315, Teller, issued Oct. 21, 1958; U.S. Pat. No. 2,900,306, Slater, issued Aug. 18, 1959, and U.S. Pat. No. 2,970,083, Bell, issued Jan. 31, 1961, have been available for quite some time. Other commercially available gelling agents which may be used include, for example, dibenzylidene monosorbitol acetal (known commercially as Millithix) and its analogs. Although useful as a gelling agent, Millithix has not been used extensively in deodorant gel stick compostions because water, which comprises as much as 25% of typical compositions, causes it to break down into its component parts, benzaldehyde and sorbitol, resulting in gel instability.
Several materials are known to have antimicrobial activity of the type that would be useful in a deodorant gel stick composition. Examples of such materials include the primary olamine salt of piroctone (known commercially as Octopirox), certain metal salts of piroctone acid (such as aluminum, sodium, potassium, zirconium, calcium and zinc metal salts), triclosan, zinc phenolsulfonate, and certain heavy metal salts of 1-hydroxy pyridinethione (such as zinc pyrithione, magnesium pyrithione, and aluminum pyrithione). The heavy metal salts of pyridinethione are active antimicrobials, bactericides, and fungicides. Certain of them are particularly adaptable to use on skin, hair, and textiles, as disclosed in U.S. Pat. No. 3,940,482, Grand, issued Feb. 24, 1976. For example, zinc pyrithione has been used for the control of dandruff, as disclosed in U.S. Pat. No. 4,345,080, Bolich, issued Aug. 17, 1982. The use of salts and derivatives of pyrithione and closely-related pyridine-N-oxide compounds in hair, skin or textile treating compositions is also taught in U.S. Pat. No. 3,412,033, Karsten, issued Nov. 19, 1968; U.S. Pat. No. 3,636,213, Gerstein, issued Jan. 18, 1972; U.S. Pat. No. 3,852,441, Kooistra, issued Dec. 3, 1974; U.S. Pat. No. 3,862,305, Bouillon, issued Jan. 21, 1975; U.S. Pat. No. 4,235,873, Packman, issued Nov. 25, 1980; and Japanese Published Application J60-23309, Lion, published Feb. 5, 1985.
Although known to have the necessary antimicrobial activity, the heavy metal salts of 1-hydroxy pyridinethione have not generally been used in deodorant gel stick applications. In the presence of the amounts of water typically found in gel sticks, such pyridinethione salts react with the soap gelling agents to form insoluble precipitates which result in a less desirable deodorant product. For example, when sodium stearate is used as the gelling agent in a gel stick where zinc pyrithione is the deodorant active, the level of water present in typical compositions (often greater than 20%) causes the formation of zinc stearate, which is ineffective, and sodium pyrithione, which is unacceptable.
U.S. Pat. No. 3,917,815, Kalopissis, issued Nov. 4, 1975, describes certain pyridine-N-oxide derivatives as actives for deodorancy in a conventional water-containing stearate-based gel stick. The compositions disclosed contain a significant amount of water. Additionally, the use of zinc pyrithione is not disclosed.
It is therefore an objective of the present invention to provide a deodorant gel stick composition, particularly a soap-based gel stick, in which heavy metal salts of 1-hydroxy pyridinethione are used as the deodorant active and the activity and integrity of the pyrithione salt are maintained.
It is a further objective of the present invention to provide a deodorant gel stick composition in which other water-sensitive components, such as dibenzylidene monosorbitol acetal gelling agent, may be effectively used without their breaking down into non-gelling and less desirable species (such as benzaldehyde).
All percentages and ratios used herein are by weight unless otherwise indicated.